Just purchased a 90 ford motorhome with a 460 4 barrel. 18k miles. Sitting for a long time. Got it started but lacked power. Removed valve cover found 5 bent push rods. Replaced and ran ok. Drove 30 miles,bent a few more. Any ideas why and what to check/do?? Any help appreciated. Motorhome stuck now 4 hours from home at a truck stop. Thanks,Gil

 

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My 460 (an '84, also in a motorhome) was bending the same pushrod repeatedly but it was caused by an extreme case of valve recession from running on a propane system that wasn't set up properly. With only 18K miles on your engine and 5 pushrods bending it sounds like the cam timing is off rather than normal wear and tear.
Do you know if the previous owner had done any work on the timing gears? Are the bent rods all intake or a mix of intake and exhaust?
Ford changed the cam timing in '72 (I believe) to meet emission standards. They set the timing gears so that the cam would be 8* retarded with respect to the crankshaft.
Engine tuners found that it was easy to set it 4* advanced which gave you much better throttle response and put your torque peak lower in the rev range. This is a cheap performance upgrade for heavy duty applications such as yours.
The previous owner may have tried this but ended up screwing things up.
There are a lot of knowledgable guys on here that should be able to give some insight.

 

The last time I saw bent push rods was when I had a few wipped out lifets and cam lobes.

 

i think that no-fear hit the nail on the head.have seen a few where valve goes deep into the seat. remove all rockers and check for taller valve stems using a straight edge. good luck and keeps us posted

 

Im an aircraft guy so I dont know if any of this applies, but we see it happen when the valve guides accumulate deposits and the valves start sticking. It could also be oil starvation to the rocker arms and they seize up. take the valve covers off and stake each valve and check for movement. Change the oil and filter(might be clogged) and thus preventing lubrication.

 

Not sure if it would cause push rod bending but I did have a problem with burning valves due to an advance weight spring coming off in the distributor which coupled with advancing the timing caused serious preignition.

John